how to quiet an engine???

[Timbone]

I am curious if this causes lower performance.

Big bump. The answer is no as you most likely have no expansion chamber.

Take a small can - it must be strong. Fill it with shredded steel wool. Make sure you have at least 1/2" round for gasses to escape and a baffle to keep the steel wool from falling out. Just weld it onto the end of the stock muffler!

 

[Frankenstein]

Big bump. The answer is no as you most likely have no expansion chamber.

Take a small can - it must be strong. Fill it with shredded steel wool. Make sure you have at least 1/2" round for gasses to escape and a baffle to keep the steel wool from falling out. Just weld it onto the end of the stock muffler!

The topic is a 4 stroke, how in the world it would be too loud being a friction drive (read: small motor) is beyond me, maybe the video he watched had a modded muffler, in either case stacking in series shouldn't do squiggly poo to a 4s.

On a 2 it might, just as you said, most likely if it has an expansion chamber, though who cares if you got it tuned in well enough you should be going fast enough that the sound you're making should pass in a split moment, not around long enough to piss people off.

 

[Steve Best]

This thread goes back to 2012, and the original poster never made any other posts than these.
I assume this old post was resurrected out of curiosity about the original question.

Exhaust is only one source of noise, once you quiet that, you start to hear the other sources.
In rough order of importance and solutions:
1) Exhaust from exit, fix leaks, longer more efficient muffler, new fiberglass packing in muffler, take off from center of the resonant chamber
2) Exhaust from pipe chamber walls, thicker or double wall (ideally with absorbent packing) resonant chamber
3) Intake noise, better filter and cover design (thicker, more absorbent materials)
4) Gear noise, gear cover sound deadening (rubber or silicon padding), thicker tacky grease
5) Cylinder noise, silicon dampers between fins, shrouding (cor-plast), tighter piston clearance
6) Chain/sprocket noises, plastic chain guards

Quiet makes the ride less tiresome, draws less public (and John Law!) ire, allows you to ride more places and lets you hear problems (detonation, mechanical) before they get worse.

 

[CurtH]

I did post out of curiosity as Steve Best mentioned. Thanks for the replies, they were helpful. I am in the research phase of motorizing my bicycle and just gathering information.